Protein-based interpenetrating networks (IPN) for tissue scaffolds/drug release

This study examined the effects of gelatin backbone modification with ethylenediaminetetraacetic dianhydride or monomethoxypolyethyleneglycol monoaldehyde, gelatin weight percent, environmental pH, and the molecular weight of polyethyleneglycol diacrylate (PEGdA) on in vitro swelling/degradation kinetics, in vivo biocompatibility, and mechanical properties of IPNs. Increasing the molecular weight of PEGdA increased the maximum swelling ratio (R/sub max/) as well as the corresponding time to reach this ratio (T/sub max/). T/sub max/ was also increased by gelatin modification. Decreasing the gelatin weight percent decreased the swelling ratio at failure (R/sub fail/). Increasing PEGdA molecular weight, modifying the gelatin backbone, and changing the gelatin weight percent had no effect on the time to reach R/sub fail/ (T/sub fail/). A preliminary in vivo study showed statistically different inflammatory responses between the IPNs and empty cage controls after 4, 7, and 14 days. The Young's modulus, ultimate tensile stress and strain of 40 wt.% gelatin 60 wt.% PEGdA 2 K were determined to be 1.26/spl plusmn/0.14 N/mm/sup 2/, 0.39/spl plusmn/0.10 N/mm/sup 2/, and 0.49/spl plusmn/0.07 mm/mm respectively. These results revealed that the degradation kinetics can be varied and tailored for a specific tissue engineering and drug delivery need. Furthermore, gelatin modification provided a myriad of chemical constituents to influence the solubility and release kinetics of loaded therapeutic molecules.